Timeout errors happen when you have a process/program takes more that the default timeout set by the runtime. In your scenario's case it is 30 seconds. You must be getting a timeout after 30 seconds. Now as other answers said, you can set your Microflow properties such that it is Asynchronous, that way browser and runtime will not wait for each other. Once the MF processing is done, should do get the PDF download option.

A quick debug to check this is: make a simple Page and call the same MF. Notice the difference.

Hey Spoorthi YU,

you getting timeout error, on button that is performing this action change microflow settings from Synchronous to Asynchronos.

This should solve your issue.

Best regards, Slavko

Did you check out these options?

https://docs.mendix.com/appstore/modules/document-generation/#624-timeout-errors 

Thanks for the answer slavko, I have changed according to what you suggested. But I am getting the below errors

Hi Ganesh, thank you for the answer. I have changed the microflow properties to asynchronous. But still i am getting the below errors.

From the screenshots above it seems like the after startup microflow might not be enabled/configured correctly, could you verify if you followed all steps described in the documentation here, especially on configuring the ASu_DocumentGeneration_Initialize microflow?

In addition, it seems like there are some issues regarding entity access as well, you will probably need to resolve these as well for the document to work.

Hope this helps!